Higgs decay to τ+τ−A possible signature of intermediate mass Higgs bosons at high energy hadron colliders

This paper considers the decay of a standard model Higgs boson into a tau pair, as a possible signature at the SSC or LHC for a Higgs boson of mass between 110 and 160 GeV. The production of the Higgs in association with a large transverse momentum jet is considered, since this may aid in reconstructing the Higgs mass. The background from the production of tau pairs via virtual photons and Z's is studied. We comment on the possible use of this process to search for a light Higgs at the Tevatron collider.     

Search for neutral minimal supersymmetric standard model Higgs bosons decaying to tau pairs produced in association with b quarks in pp collisions at √s = 1.96 TeV

We report results from a search for neutral Higgs bosons produced in association with b quarks using data recorded by the D0 experiment at the Fermilab Tevatron Collider and corresponding to an integrated luminosity of 7.3 fb(-1). This production mode can be enhanced in several extensions of the standard model (SM) such as in its minimal supersymmetric extension (MSSM) at high tanβ. We search for Higgs bosons decaying to tau pairs with one tau decaying to a muon and neutrinos and the other to hadrons. The data are found to be consistent with SM expectations, and we set upper limits on the cross section times branching ratio in the Higgs boson mass range from 90 to 320 GeV/c(2). We interpret our result in the MSSM parameter space, excluding tanβ values down to 25 for Higgs boson masses below 170 GeV/c(2).     

Determining the CP parity of Higgs bosons via their tau decay channels at the Large Hadron Collider

If neutral Higgs bosons are discovered at the CERN Large Hadron Collider (LHC), then an important subsequent issue will be the investigation of their CP nature. Higgs boson decays into tau lepton pairs are particularly suited in this respect. By analyzing the three charged pion decay modes of the tau leptons and taking expected measurement uncertainties at the LHC into account, we show that the CP properties of a Higgs boson can be pinned down with appropriately chosen observables, provided that sufficiently large event numbers will eventually be available.     

A study of the measurement precision of the Higgs boson decaying into tau pairs at the ILC

We evaluate the measurement precision of the production cross section times the branching ratio of the Higgs boson decaying into tau lepton pairs at the International Linear Collider (ILC). We analyze various final states associated with the main production mechanisms of the Higgs boson, the Higgs-strahlung and WW-fusion processes. The statistical precision of the production cross section times the branching ratio is estimated to be 2.6 and 6.9 % for the Higgs-strahlung and WW-fusion processes, respectively, with the nominal integrated luminosities assumed in the ILC Technical Design Report; the precision improves to 1.0 and 3.4 % with the running scenario including possible luminosity upgrades. The study provides a reference performance of the ILC for future phenomenological analyses.     

h --> mutau at Hadron colliders

We study the observability for a lepton flavor-changing decay of a Higgs boson h--> mutau at Hadron colliders. Flavor-changing couplings of a Higgs boson exist at tree level in models with multiple Higgs doublets. The hmutau coupling is particularly motivated by the favorable interpretation of nu(mu)-nu(tau) oscillation. We find that at the Tevatron run II the unique mutau signature could serve as the Higgs discovery channel, surpassing expectations for Higgs boson searches in the SM and in a large parameter region of the MSSM. The sensitivity will be greatly improved at the LHC, beyond the coverage at a muon collider Higgs factory.     

Tau leptons and the decay H → ττ at CMS

The tau lepton and its reconstruction at CMS are briefly described. This is followed by a summary of the searches for a standard model Higgs boson and neutral Higgs bosons from the minimal supersymmetric extension of the standard model decaying into pairs of tau leptons performed by the CMS Collaboration. The data samples used in these searches were collected during the first running period of the LHC and contain 4.9 fb^?1 at \(\sqrt {s}=7\,\text {TeV}\) and 19.7 fb^?1 at \(\sqrt {s}=8\,\text {TeV}\).     

The hadronic tau decay signature of a heavy charged Higgs boson at LHC

The hadronic tau decay channel offers by far the best signature for heavy charged Higgs boson search at the LHC in the large tanβ region. By exploiting the distinct polarization of the tau and its large transverse mass, along with the accompanying missing–p_T, one can probe for a charged Higgs boson up to a mass of about 600 GeV in an essentially background-free environment. The transverse mass distribution of the tau jet also provides a fairly unambiguous estimate of the charged Higgs boson mass.     

Search for very light CP-odd Higgs Boson in radiative decays of Upsilon(1S)

We search for a non-SM-like CP-odd Higgs boson (a(1)(0)) decaying to tau(+)tau(-) or mu(+)mu(-) in radiative decays of the Upsilon(1S). No significant signal is found, and upper limits on the product branching ratios are set. Our tau(+)tau(-) results are almost 2 orders of magnitude more stringent than previous upper limits. Our data provide no evidence for a Higgs state with a mass of 214 MeV decaying to mu(+)mu(-), previously proposed as an explanation for 3 Sigma(+)-->pmu(+)mu(-) events observed by the HyperCP experiment. Our results constrain NMSSM models.     

Prospects for B physics with the ATLAS and CMS detectors

The possibility of observing the radion using the ATLAS detector at the LHC is investigated. Studies on searches for the Standard Model Higgs with the ATLAS detector are re-interpreted to obtain limits on radion decay to γγ and ZZ^(*). The observability of radion decays into Higgs pairs, which subsequently decay into or is then estimated.     

Production of neutral Higgs-boson pairs at LHC

The reconstruction of the Higgs potential in the Standard Model or supersymmetric theories demands the measurement of the trilinear Higgs couplings. These couplings affect the multiple production of Higgs bosons at high energy colliders. We present a systematic overview of the cross sections for the production of pairs of (light) neutral Higgs bosons at the LHC. The analysis is carried out for the Standard Model and its minimal supersymmetric extension. Received: 30 March 1999 / Published online: 28 May 1999     

Direct search for charged higgs bosons in decays of top quarks

We present a search for charged Higgs bosons in decays of pair-produced top quarks in pp collisions at sqrt[s] = 1.8 TeV recorded by the D0 detector at the Fermilab Tevatron collider. With no evidence for signal, we exclude most regions of the ( M(H+/-),tan(beta)) parameter space where the decay t--> H(+)b has a branching fraction >0.36 and B(H+/--->tau(nu)(tau)) is large.     

Search for Higgs bosons decaying to tau pairs in pp over collisions with the D0 detector

We present a search for the production of neutral Higgs bosons varphi decaying into tau+tau - final states in pp over collisions at a center-of-mass energy of 1.96 TeV. The data, corresponding to an integrated luminosity of approximately 1 fb(-1), were collected by the D0 experiment at the Fermilab Tevatron Collider. Limits on the production cross section times branching ratio are set. The results are interpreted in the minimal supersymmetric standard model yielding limits that are the most stringent to date at hadron colliders.     

Mass restricting variables in semi-invisible production at the LHC

We outline some of the popular mass restricting variables for the semi-invisible productions at the Large Hadron Collider. In this context, heavy resonating mass, if produced through antler decay topology may already be detectable. New mass variables constructed by applying this mass constraint proved to have an array of interesting properties, including a new kink solution at the true masses of the produced particles. This enables one to measure the mass of the invisible particle and the parent particle simultaneously. This variable in turn can also be applied in reconstructing such events with the momenta of invisible particles. This feature is further demonstrated with the Higgs boson decaying into a pair of third-generation tau-lepton (\(\tau \)) and thus exploring direct Higgs coupling with the leptonic sector. Dominant discovery signatures rely upon the hadronic decay of tau which is associated with a pair of invisible neutrinos. Exploiting the already measured Higgs mass bound, present technique is capable of providing unique event reconstruction. Moreover, a significant efficiency enhancement is demonstrated in comparison with the existing methods.     

Future e(+)e(-) colliders' sensitivity to Hbb coupling and CP violation

We perform a complete simulation of the process e(+)e(-)-->bbvv, where nu can be an electron, muon, or tau neutrino, in the context of a general Higgs coupling to b quarks. We parametrize the Hbb; coupling as (m(b)/v)(a+igamma(5)b). Taking into account interference effects between pure Higgs and Standard Model contributions, we find that sensitivities of the order of 2% and 20% can be obtained at a future e(+)e(-) collider for deviations of the a and b parameters, respectively, from their Standard Model values. Combining our analysis with an independent measurement of Gamma(H-->bb) can provide evidence about the CP nature of the Higgs sector.     

Determining the chirality of Yukawa couplings via single charged Higgs boson production in polarized photon collisions

When the charged Higgs boson is too heavy to be produced in pairs, the predominant production mechanism at linear colliders is via the single charged Higgs boson production processes, such as e(-)e(+)-->bcH+,taunuH+ and gammagamma-->bcH+,taunuH+. We show that the yield of a heavy charged Higgs boson at a gammagamma collider is typically 1 or 2 orders of magnitude larger than that at an e(-)e(+) collider. Furthermore, a polarized gammagamma collider can determine the chirality of the Yukawa couplings of fermions with charged Higgs boson via single charged Higgs boson production and, thus, discriminate models of new physics.     

Probing the Stau－Stau－Higgs Couplings in the MSSM at NLC

In the minimal supersymmetric standard model (MSSM) with CP violating phases, this paper discusses the production of the lJghtest neutral Higgs boson in association with tau sleptons at future high-energy e^ e^- linear colliders. In parameter space of the constrained MSSM, the production cross section of e^ e^→h^0T1 T1^- can be very substantial at high energies. This process would provide a production mechanism for probing couplings of neutral Higgs bosoas to tau sleptons as well as some soft supersymmetric breaking parameters at next linear colliders.     

Observation of Upsilon(3S)-->tau+tau- and tests of lepton universality in Upsilon decays

Using data collected with the CLEO III detector at the CESR e+e- collider, we report on a first observation of the decay Upsilon(3S)-->tau+tau-, and precisely measure the ratio of branching fractions of Upsilon(nS), n=1, 2, 3, to tau+tau- and mu+mu- final states, finding agreement with expectations from lepton universality. We derive absolute branching fractions for these decays, and also set a limit on the influence of a low mass CP-odd Higgs boson in the decay of the Upsilon(1S).     

Tau reconstruction and identification algorithm

CMS has developed sophisticated tau identification algorithms for tau hadronic decay modes. Production of tau lepton decaying to hadrons are studied at 7 TeV centre-of-mass energy with 2011 collision data collected by CMS detector and has been used to measure the performance of tau identification algorithms by measuring identification efficiency and misidentification rates from electrons, muons and hadronic jets. These algorithms enable extended reach for the searches for MSSM Higgs, Z and other exotic particles.     

Uplifted supersymmetric Higgs region

We show that the parameter space of the Minimal Supersymmetric Standard Model includes a region where the down-type fermion masses are generated by the loop-induced couplings to the up-type Higgs doublet. In this region the down-type Higgs doublet does not acquire a vacuum expectation value at tree level, and has sizable couplings in the superpotential to the tau leptons and bottom quarks. Besides a light standard-like Higgs boson, the Higgs spectrum includes the nearly degenerate states of a heavy spin-0 doublet which can be produced through their couplings to the b quark and decay predominantly into τ ⁺ τ ^? or τν.